This invention relates to an improved method and apparatus for detecting gunshots and recognizing their characteristic waveform as separate and different from other common noises, particularly those encountered in a law enforcement environment.
The ability to distinguish a gunshot, regardless of the type of weapon fired, is often difficult due to the ambient noise typically present in many law enforcement environments. In security applications, detecting a gunshot by ear is not feasible as a police officer or other person capable of recognizing the shot and responding in an appropriate manner is often not present. Therefore, remote detection and monitoring are required in order to adequately protect retail establishments, other public places and dwellings in order to prevent criminal activity and ensure a prompt response when such activity occurs.
It has been found that the audio signature (amplitude envelope) of a gunshot has defined characteristics irrespective of whether the shot is produced by firing a handgun, a rifle or a shotgun. The common thread identifying these various types of gunshots is an extremely sharp rise time characteristic in all cases and a predictable decay in amplitude thereafter. Therefore, although the amplitude of the gunshot will, of course, depend upon the cartridge that is expended, the type of weapon and distance, the amplitude versus time format can be predicted.